Vitali Klitschko, who is 40-2 with 38 knockouts, has one of the best knockout percentages in heavyweight boxing history and has three times won a piece of the heavyweight title.
A variety of back and knee injuries forced to him to give up his belt and go into a nearly four-year retirement, but since returning to the ring in October 2008, Klitschko has laid waste to his five opponents. He has scarcely lost any of the 49 rounds he's boxed during his comeback, which began with an eighth-round demolition of Samuel Peter to regain his old belt.
The challengers have fallen one by one -- Juan Carlos Gomez in nine one-sided rounds; Chris Arreola's corner threw in the towel after 10 rounds of punishment; Kevin Johnson went the distance, but did not win one second of the fight; and Albert Sosnowski got drilled in the 10th round in May as the busy Klitschko looks to make up for those lost years.
He will fight for the sixth time in 24 months when he defends his title against American Shannon Briggs, a former champion, on Saturday at the O2 World Arena in Hamburg, Germany. ESPN3.com will have live coverage at 5 p.m. ET with a taped replay on ESPN at 2 p.m. ET Sunday. ESPN Deportes will replay the fight Saturday at 8 p.m. ET.
Yet for all of Klitschko's accomplishments, he is not even the best heavyweight in his family, according to most experts and Klitschko himself. Instead, his baby brother, Wladimir Klitschko, owner of the lineal title and two alphabet belts, has been anointed as the baddest man on the planet.
"Wladimir has much more skills, he is younger and he has more power than me," Klitschko said over the phone from Hamburg this week. "He is better than me. My brother has much more skills, but boxing fans can make speculation about who is the best of two brothers. They make the competition on the Internet or on computer games to see who is the stronger brother. It's very good to think about that, to make that imaginary fight, but I am very happy to be with my brother as the strongest fighter in the world."
The Klitschko brothers, best friends too, have vowed ad nauseam that they will never fight each other.
As competitive as Vitali Klitschko is in the ring, he swears he does not have that same competitive spirit when it comes to his brother, although their few sparring sessions when they were younger got so heated and intense they had to stop. They haven't sparred in many years.
"I am very happy for my brother Wladimir's success," Klitschko said. "Believe it or not, for me it's not a big difference on who people say is best. If my brother have a belt, it's exactly the same as me having the belt. I used to have the Ring [magazine] title [before giving up to retire] and now it belongs to Wladimir, and I am very happy for that. It's a funny feeling. If my brother beats his opponent, I feel myself like I am the winner. We share our wins together. It's crazy feeling, but amazing feeling to have a brother who is also strongest fighter in the world."
Even if his retirement cost him his place atop the heavyweight rankings, it was worth it for Klitschko. He said the time off allowed him to heal all of his various ailments and that even at age 39, he feels as good as he ever has.
Based on his performances since returning, he sure looks like he is being honest about that.
"I've been amazed by how well I have been since coming back. I am very happy," he said. "The line of injuries in the past, they are behind me. I feel great. I have pretty young sparring partners, 25, 30 years old. They have a really hard time. I am very close to 40, but I am in great, great shape. I can't explain it. I can tell you I feel my best."
One thing Klitschko is a bit tired of are the endless questions about much longer he will fight. He said as long as he continues to feel good and fight as well as he ever has, there is no telling how long he'll be around terrorizing the heavyweight division.
"How long I fight, nobody knows," Klitschko said with a laugh. "This is professional boxing, so every fight can be the last fight. But I had a break because of the injuries. I live a healthy lifestyle. I don't drink, don't eat too much, go to the fitness studio and train every day. I used the break to get even stronger."
Said Tom Loeffler, the managing director of Klitscko's K2 Promotions, "Vitali is the sharpest now that he has ever been. That is what his trainer, Fritz Sdunek, says. He says he has not seen Vitali look this good as he has for this fight."
If that's the case, the 38-year-old Briggs (51-5-1, 45 KOs), already a huge underdog, could be in even more serious trouble than most expect against a champion who never been off his feet. He seems to have really annoyed Klitschko by talking endlessly about his asthma.
Klitschko then called Briggs' condition a way for him to make excuses for when he loses, and Briggs pounded.
"There are 300 million people in the world with asthma, and not one of them would agree with Vitali Klitschko that it's nothing serious. Isn't he supposed to be a doctor? A doctor of what?" said Briggs, mocking Klitschko's Ph.D. in sports science. "I am now personally dedicating my knockout punch to the sufferers of asthma worldwide that Vitali has offended. I plan on being a three-time world champion who respects people and their challenges."
Klitschko, however, will not back off his stance that Briggs' asthma is an excuse waiting to happen. Briggs used asthma as a way to explain his desultory decision loss to Sultan Ibragimov in 2007, a loss that cost him a belt and sent him into a 2½-year retirement. He returned to score four consecutive first-round knockouts, although one was erased and changed to a no-contest because Briggs tested positive for a banned substance after the December 2009 fight. Briggs claimed the positive test was the result of the medication he takes for his asthma.
"I don't want to explain about my problems that I had in the past. He shouldn't talk about his problems either," Klitschko said. "He decided to go into the ring. He has huge boxing experience, he fights 12 rounds, he was world champion. He prepares himself to do the fight and he's prepared asthma as excuse if he lose the fight.
"My opinion is when he loses it will be great excuse. If he is sick, why does he go inside the ring? It's not fair. Don't explain the problem before the fight. Are you ready or not? If you're ready, go in the ring and let's fight. No talking about the problems."
Problems or not, Klitschko says he knows how the fight will turn out.
"I don't believe the fight will be by point decision," he said. "I'm looking for the knockout of Shannon Briggs."
Dan Rafael is the boxing writer for ESPN.com. Follow him on Twitter @danrafaelespn.